The invention relates to a hob having at least one inductor, at least one inverter and a switching apparatus.
An induction hob having a plurality of inductors, with one inverter per inductor, an electronic switching apparatus and a detection circuit for detection of cooking utensils, is known from DE 42 08 254 A1. The switching apparatus opens and closes a circuit between the inductor and the inverter, so that, when the switching apparatus is in a first switch position, it makes a connection between the inverter and the inductor and, when it is a second switch position, it interrupts the connection between the inverter and the inductor.
In order to detect cooking utensils, a microcomputer initiates the closing of one of the switches in the switching apparatus, in order to connect one of the inductors during a semi-oscillation of the heater voltage to the inverter assigned to this inductor. Any attenuation in the oscillation system is determined from a voltage amplitude at a sampling point or from a drop in the voltage. The presence or existence of a cooking utensil is indicated by sufficient attenuation. The inductor is automatically activated following the detection of a cooking utensil.
The continued supply of current at full amplitude to the inductor during standby operation consumes a large amount of energy compared to pan detection devices that use separate measurement sensors operated with a low measuring voltage. However, the provision of separate measurement sensors is costly and time-consuming compared to the use of inductors both as heating elements and as sensors.